An application service provider (ASP) hosts applications for multiple customers (that is, client organisations), using a shared computing infrastructure, often termed a server farm. The ASP takes advantage of economies of scale (in terms of redundancy, peak load handling, technical skills, etc.), and of the need for customers to focus on core competencies rather than complex information technology management. Since the computing infrastructure is owned by the ASP and shared amongst customers, the ASP has ample opportunity for improving the utilization of its resources, and hence providing a cost-effective service.
In view of the above, there is a clear trend for corporate users to outsource their applications through ASPs, for economic, technological, and competitive reasons. At present, most ASPs provide simple services such as web hosting, with particular servers dedicated to respective customers. Other ASPs allow servers to be shared in relatively static manner, with very simple service level agreements (SLAs) governing the provision of these services.
One existing approach to improving machine use involves the allocation and deallocation of entire machines between customers. This approach requires the customer to specify their needs in terms of lower and upper limits on number of machines at that customer's disposal, implying the need for the customer to be technically knowledgeable. This is a reasonable proposition for large corporate clients, but is generally not suitable for small and medium sized enterprises.
An improved arrangement has been proposed by Ensim Corporation of Sunnyvale, Calif. This proposed arrangement provides application hosting using the concept of machine fractions. Ensim's solution allows ASPs to securely share server resources between customers, as well as manage the deployment of applications across the server farm by supporting what are termed private servers (PSs). Each PS can run any off-the-shelf applications supported on the physical server. The Ensim system also offers management primitives for recovering failed PSs, migrating customers across PSs and machines, and increasing PS resources manually. From a single console, ASPs can provision and manage multiple PSs. The applications to be hosted need only be web-hosting ready, and do not need any further modifications.
Despite various advantages, the arrangement proposed by Ensim has various limitations. The PSs are relatively static in the sense that each PS guarantees a minimum availability of physical server resources. As a result, the solution provided by Ensim is still relatively inefficient in its use of resources. Also, system management must be done manually, via a console.
In view of the above, a need clearly exists for an improved solution for hosting applications which at least attempts to address these and other limitations associated with existing techniques.